Method and apparatus for stretching fabrics



Dec. 23, 1930. A. BOSSHARD 1,736,183

METHOD ANITAPPARATUS FOR STRETCHING FABRICS Filed July 7, 1928 IN V ENTOR.

' 15 scribed.

Patented Dec. "23, 1930.

' meane- UNITED STATES PATENT o Frce ARNOLD BOSSHARD, OF ARBON,SWITZERLAND, ASSIGNOR T SIR- J'AMES FARMER NORTON & COMPANY LEMITED, OFLANCASHIBE, ENGLAND, A BRITISH COMPANY METHOD AnnAPPARArUs FORs'ran'rcnme FABRICS Application filed July 7, 1928, Serial No. 290,961,and in Germany Februai-y 3, 11928.

and useful method and device for stretching:

a web of. fabric in breadth. V Objects and advantages of the inventionwill be set forth in part hereinafter and in part will be obviousherefrom, or may be learned by practice with theinvention, the samebeing realized and attained by means 19 of. the instrumentalities andcombinations pointed out in theappended claims.

The invention consists in the. novel parts, constructions, arrangements,combinations and improvements herein shown and de- The accompanyingdrawings, referred to herein and'constituting a part hereof, illustrateoneembodimentlof the invention and together. with the descriptiomserveto ex- 1 as plain the principles of the invention.

7 .Of the drawingsse- V Fig. 1 is a fragmenjary, vertical section of achainless merce izing machine embodying the invention;

, Fig. 2 isa detail stretching and plan view of a broadroller embodyingthe .-invention 40 very thorough, efficient and evenly distrib:

uted stretching action, utilizing all the power of the machine;eliminatingthe warping of the tissue and displacement of the threads inthe fabric and preventinga shoving effect by the stretching devices'with consequent injury. and disfiguring of thefabric.

The usual-apparatus forstretching a web of fabric in breadth, employedin machines 'ofthetype indicated, consists of a series of breads e chzea oll r eac comprising. a

Fig. 3 is a diagrammaticshowingof the curvedaxle with a plurality ofroller segments or cylindrical, members rotatively mounted and adaptedto turn freely thereon.

The roller segments are ordinarily interlocked by clutching-teeth or byfrictional engagement so that they turn together, and may be positivelydriven by suitable driving mechanism. The web of; fabric to be stretchedifn'breadth is progressed longitudinally through the'seriesrof rollerspassing over each broad-stretching roller in sequence, the curvature ofthe axle causing the fabric to be stretched laterally as the web movesforwardly through the rollers. V V e r In the broad-stretching rollersat present employed, each roller segment or cylindrical section is ofuniform diameter throughout its length and all the segments on the axleare of the same diameter, whereby any element of the periphery of agiven segment is substantially parallel tothe part of the axle aboutwhich it rotates. Hence, each roller segment has the same peripheralvelocity in a direct-ion perpendlcular to its respective portion of theaxle, each segment being of the same diameter and having the same numberof revolutions about the axle as every other segment As a result of thisconstruction, the web of fabric in passing over the broadstretchingrollers is not stretched evenly throughoutits width, but receives adifferent longitudinal and lateralstretching force at different pointsacross the web, so that the fabric is warped or distor ed in thedirection of the weft threads. V The reason for the warping ordistortion of thefabric will be clear when it is considered thatdifferent parts ofthe web progressing through the series ofbroad-stretching rollers are subjected to different; stretching effects.The centraljportion of the web, which runs overthe center rollersegment, issubjected to a forward progressing force proportional to theforward peripheral velocity of that seg-.

ment. Since the axle of the stretching roller is curved rearwa-rdly onboth sides of the center, the forward'peripheral velocities of theroller segments on either side of the center segment willbe less thanthat of -the center segment, because, being-of the same diameter andturning with the same angular speed about an axis inclined to that ofthe center segment, the forward progressing force of the side rollerswill be only a component of their peripheral velocity. In other words,the maximum peripheral velocity of each roller segment is not trulyforward in the direction of progression of the web, but is in a. direct1 perpendicular to the axis about which the n segment turns.

The effect of the hereinbefore-described differences in forwardprogressing force of the roller segments at different points along thecurved roller is to feed the portions of the web at different speeds.The lateral edges of the web are progressed much more slowly than thecenter portion, and conse quently the forward movement of a weft threadis different at different parts thereof, so that the fabric isdistorted, warped or pulled out of line in the direction of the weftthread. Since the broae-stretching rollers are usually ar 'anged inseries, the warping effect is cumulative. each roller adding itsdisplacing force to the progressing web. Of course, the warping onlygoes as far as the lasticity of the tissue will permit. The remainingunused power, or more properly, the difference in power at the differentparts oi the roller, applies itself to shoving the fabric through therollers, which further distorts the fabric and greatly injures anddisfigures the cloth. Furthermore, due primarily to the displacement ofthe warp thread, the brezul-stretehing effect is greatly reduced and themechanism does not realize its full eiiiciency in this direction.

The above-mentioned disadvantages and defects in the operation of theusual type of broad-stretching roller have long been recognized in theart and in order to remedy the results thereof, auxiliary mechanisms andarrangemeins nave been resorted to for restor ing the adjustn'ient ofthe threads in the fabric after removal from the broad-stretchmachine.

The present invention overcomes the d: advantages of the presentln'oad-stretcl-iing rollers and does away with the necessi y forauxiliary d vices for the purpose described. The present preferredembodiment of the invention, broadly considered. comprises a brl-strctchinq roller provided with'a plurality of roller ments, thediametersof the 'incnts being 11 that the power of all the nents,effective in the direction of the warp thread, is equally great. Thediameters of the rollers acrease toward both sides of the axle inproportion to the radius. of the curve of the axle on which they rotate.In other words, all the segn'lents of the broadstretching roller of thepresent invention move the fabric in the warp thread direction with thesame rapidity, so that the weft threads can no longer become warped.

By virtue of the present invention, not only are the injurious effectsof the usual broadstretching rollers eliminated, but the actualstretching effect is much stronger, as the remaining power, or componentof the stretching roller in the lateral direction can be reallyeffective in the direction of the weft thread, which is not possiblewhen the threads of the fabric are displaced as hercinbeforedescribed.

It will be understood that the fore oing general des/ 'iption, and thefollmvn detailed description as well, are explanatory and exemplary ofthe invention but are not restrictive thereof.

Referring now in detail to the embodiment oft-he invention, illustratedby way of example in the accompanying drawings, Fig. 1 shows anexemplary embodiment of the invention as applied to the broad-stretchingrollers of a chainless mercerizing machine, such for instance as thatdisclosed and described in my copending application, Ser. No. 119,137,filed June 28, 1926. It will be understood, however, that the embodimentshown is explanatory and illustrative but not restrictive of theinvention, which may be employed in any kind of machine for handlingfabric or the like.

The machine frame 1 is provided with a plurality of broad stretchingrollers mounted on curved axles 2, suitably fixed in the frame andarranged sequentially in a substantially horizontal row, whereby theyweb of fabric passes through the machine from left to right, beingsequentially subjected to the broadstretchiug effect of each roller. Theroller segments 3, d, 11, 12, 13, 14: and 15 are mounted to turn on theaxles, the curvature of the axle bringing the abutting ends of theroller segments into frictional engagement along the inner or concaveside of the curve, whereby the segments are adapted to turn together topropel the web of fabric forwardly through the machine while stretchingit in breadth.

Suitable driving mechanism may be provided for rotating the rollersegments on the axles. As embodied, the driving gears 6 and 7 mounted onshafts 8 and 9 and driven from any suitable driving source, are adaptedto mesh with gear wheels 10 at the ends of the axles. The gear wheels 10of the axles are likewise adapted to intermesh with each othr, wherebyall the broad-stretching rollers are operatively connected.

Referring now to the construction of the broad-stretching roller itself,the invention provides a plurality of roller segments rotatably mountedon the axle 2, the centrally disposed segment 3 being substantially atrue circular cylinder of the same diameter throughout. The rollersegments 4 on either side ofthe segment 3 are of varying diame-.

ter, comprising preferably frustra of a cone,

whose smaller base is substantially of the diameter of segment 3 andwhose diameter is increased proportionately to the radius of the curveof the axle 2. That is, the diametric increase of the segment isproportional to the sharpness or rate of curvature of the particularaxle on which it is mountedfThe roller segments 11 next in the lateralsequence outwardly from the center of the axle have bases substantiallyequal in diameter to that of the outer bases of segments 4, thediameters of segments 11 increasing along the axle in the proportionindicated. The remaining laterally disposed segments, 12, 13 and 14likewise comprise cone frustra whose diameters increase toward theendsof the axle sequentially in the same proportion.

Referring now to the operation of the invention, under the turninginfluence of the driving mechanism, central roller 3 rotates with aforward peripheral velocity of the value V and progressesthe centralportion of the web forwardly with a corresponding force, as indicatedinFig. 3. The segments 15, at the extremities ofthe axle rotate with aperipheral velocity V which is exerted in a direction perpendicular tothat portion of the axle about which section 15 revolves. There isconsequently a resolved force C in the forwardly progressing direction.Ac-

cording to the invention, the diameters of seg- V ment 15, and of theintervening segments 11-14l are so proportioned that the forward 7component C of the peripheral velocity and progressing force will alwaysbe equal to that V of circular roller segment Hence, there is provided abroad-stretching roller having a forward peripheral velocity and forwardprogressing force which is the same atrall points alongthe roller;

The vector C represents the breadthstretching eflect or power of theroller segment 15 in the lateral direction. It will be noted that thisvector also increases laterally of the roller so thatthebreadth-stretching effect in the roller of the present inventionis muchgreater than that developed in the old type of roller where the rollersegments were all of the same diameter.

The invention in its broader'aspects is not limited to the specificmechanisms shown and described but departures may be made therefromwithin the scope of the accompanying claims without departing from theprinciplesv .ofthe invention and without sacrificing its chiefadvantages. r

What I claimis 1. A breadth stretching device for fabrics comprising acurved axle, a plurality of V roller segments of differentdiametersrotatively mounted on the axleffor progressinga web of fabricforwardly while stretching it in breadth, the diameters of said segmentsincreasing progressively toward the lateral edges ofthe web of fabricwhereby the roller segments are adapted to progress the web forwardlywith substantially equal velocity grossing velocity substantially equalat all points along a transverse thread.

3. In a fabric stretching mechanism hav ing a plurality ofcurved-breadth-stretching rollers arranged in juxtaposed sequencewhereby a web of fabric progresses under and over alternate rollers tobe stretched in breadth as it progresses lengthwise, the coinbination'ofconical roller segments on the curved axles of said roller members forimparting a substantially equal forward-progrossing force to the web atall points across theroller, and means for driving said'segmentstogether. i

4. A breadth stretching device for a web I of-fabric comprisingaplurality of rollers mounted on a curved shaft, the diameters ofadjacent rollers increasing outwardly'from the smallest roll at themid-portion of the shaft, the distances from the shaft to the pe ripheryof each roller measured on lines parallel to the forward movement of theweb being substantially equal.

5. A breadth-stretching device for a wet of fabric comprising aplurality of rollers V of different diameters mounted on a curved shaftand adapted to turn together, the diameters of the rollers'being soproportioned to their distances from the midsection of the shaft thatthe peripheral velocities of; the rollers in the direction of the webtravel are substantially equal.

6. A breadtl1-tensioning device for a web of fabric comprising'a curvedaxle, a plurality of conoidal roller segments rotatively mounted thereonfor progressing a web of fabric forwardly while stretching ittransversely, the diameters of said'conoidal segmerits increasingprogressively outwardly from a median point on the axle in suchproportion that the forward component of the peripheral velocity of eachsegment is substantially equal, and means for rotating said segmentstogether.

In testimony whereof, I have signed my name to this specification.

ARNOLD BOSSHARD.

ISO

